The present invention relates to aquatic plants. More particularly, the present invention relates to harvesting aquatic plants from a body of water.
There has been an increasing interest in the use of aquatic plants as a food source or cash crop. Additionally, aquatic plants have found use in waste water treatment. Growing and harvesting aquatic plants has thus become an increasingly important industry.
Improving the efficiency of growth and harvest techniques is an important factor in continued expansion in the industry of aquatic plant production. U.S. Pat. No. 4,536,998 describes a system of growing aquatic plants which increases yield and the effectiveness of those plants for waste water treatment. Continued improvement of harvesting techniques is important to continued industry growth.
An aquatic plant, such as duckweed, grows near the surface of a body of water, and tends to have a rather large volume relative to its weight, i.e., a relatively low density. However, aquatic plants can take on a variety of forms depending on many factors, including its life cycle stage, density and root length. In order to harvest the plant, a harvesting device must be suited to lift the aquatic plant in densities ranging from a thin "mono-layer" approximately 1/10 of an inch thick, to a 1"-4" thick semi-solid mat of aquatic plants with the consistency of mud. In the "mono-layer" state, the aquatic plant disburses to fill gaps on the water surface. In the "semi-solid" state, the aquatic plant adheres to itself resisting separation.
In the past, aquatic plants were harvested from a body of water by a floating harvester. The aquatic plants were collected by the harvester and hauled to the shore where they were off-loaded. Such a system is inherently inefficient due to the travel time required by the harvester in moving from the area of the pond which it is harvesting to the shore with a full load, and then returning to the harvesting area. As the size of waste water ponds or lagoons increases, the cost of harvesting drastically increases due to the travel time of the harvester to and from the unloading zone on shore. Further, the cost of additional harvesters is prohibitively expensive and requires additional manpower.